=over

=item $LAST_PAREN_MATCH

=item $+
X<$+> X<$LAST_PAREN_MATCH>

The text matched by the highest used capture group of the last
successful search pattern.  It is logically equivalent to the highest
numbered capture variable (C<$1>, C<$2>, ...) which has a defined value.

This is useful if you don't know which one of a set of alternative patterns
matched.  For example:

    /Version: (.*)|Revision: (.*)/ && ($rev = $+);

This variable is read-only and dynamically-scoped.

Mnemonic: be positive and forward looking.

=back